The invention relates to a trailer coupling for motor vehicles, comprising a coupling ball carrier which can be mounted on a vehicle body and a coupling ball with a ball body which has a ball surface extending between a ball attachment and an upper end surface of the ball body.
Trailer couplings of this type are known from the state of the art.
The coupling ball carrier can comprise a customary cross member mounted on a vehicle body with longitudinal members and a ball neck held on the cross member, wherein the ball neck is securely connected to the cross member.
The coupling ball carrier can, however, also comprise such a cross member with a removable ball neck or the coupling ball carrier can comprise a ball neck pivotable relative to the cross member.
The ball surface of the ball body comprises an appreciable part of a complete spherical surface but, as a rule, does not represent a complete spherical surface since, on the one hand, the ball body is seated on a ball attachment and, on the other hand, the ball body has in many cases an upper end surface in the form of a flattened area on a side located opposite the ball attachment and so the ball surface extends between the ball attachment and the upper end surface in the form of a flattened area but does not encompass it.
The object underlying the invention is to detect a body engaging on the coupling ball with respect to its form and/or alignment.